salt: Characteristics and Classification of Salts salt Characteristics and Classification of Salts The most familiar salt is sodium chloride , the principal component of common table salt. Sodium chloride, NaCl, and water, H2O, are formed by neutralization of sodium hydroxide, NaOH, a base, with hydrogen chloride, HCl, an acid: HCl+NaOH→NaCl+H2O. Most salts are ionic compounds (see chemical bond ); they are made up of ions rather than molecules. The chemical formula for an ionic salt is an empirical formula; it does not represent a molecule but shows the proportion of atoms of the elements that make up the salt. The formula for sodium chloride, NaCl, indicates that equal numbers of sodium and chlorine atoms combine to form the salt. In the reaction of sodium with chlorine, each sodium atom loses an electron, becoming positively charged, and each chlorine atom gains an electron, becoming negatively charged (see oxidation and reduction ); there are equal numbers of positively charged sodium ions and negatively charged chloride ions in sodium chloride. The ions in a solid salt are usually arranged in a definite crystalline structure, each positive ion being associated with a fixed number of negative ions, and vice versa.

A salt that has neither hydrogen (H) nor hydroxyl (OH) in its formula, e.g., sodium chloride (NaCl), is called a normal salt. A salt that has hydrogen in its formula, e.g., sodium bicarbonate (NaHCO3), is called an acid salt. A salt that has hydroxyl in its formula, e.g., basic lead nitrate (Pb[OH]NO3), is called a basic salt. Since a salt may react with a solvent to yield different ions than were present in the salt (see hydrolysis ), a solution of a normal salt may be acidic or basic; e.g., trisodium phosphate, Na3PO4, dissolves in and reacts with water to form a basic solution. In addition to being classified as normal, acid, or basic, salts are categorized as simple salts, double salts, or complex salts. Simple salts, e.g., sodium chloride, contain only one kind of positive ion (other than the hydrogen ion in acid salts). Double salts contain two different positive ions, e.g., the mineral dolomite, or calcium magnesium carbonate, CaMg(CO3)2. Alums are a special kind of double salt.

Complex salts, e.g., potassium ferricyanide, K3Fe(CN)6, contain a complex ion that does not dissociate in solution. A hydrate is a salt that includes water in its solid crystalline form; Glauber's salt and Epsom salts are hydrates. Salts are often grouped according to the negative ion they contain, e.g., bicarbonate or carbonate , chlorate , chloride , cyanide , fulminate , nitrate , phosphate , silicate , sulfate , or sulfide . Sections in this article: Sodium - Element information, properties and uses | Periodic Table Chemistry in its element: sodium (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) This week an essential element with a split personality. Here's David Read. David Read Sodium, like most elements in the periodic table could be said to have a dual personality. On one side it is an essential nutrient for most living things, and yet, due to its reactive nature is also capable of wreaking havoc if you happen to combine it with something you shouldn't. As such sodium is found naturally only in compounds and never as the free element.

Even so it is highly abundant, accounting for around 2.6 per cent of the earths crust by weight. Its most common compounds include dissolved sodium chloride (or table salt), its solid form, halite and as a charge balancing cation in zeolites. Aside from being an essential nutrient, the story of man and sodium is said to begin all the way back in the time of the Pharaohs in Ancient Egypt, with the first recorded mention of a sodium compound in the form of hieroglyphics. It is difficult to describe a pictogram through speech but imagine a squiggly line over the top of a hollow eye-shape, over the top of a semicircle, with a left-facing vulture image next to them all. This pictogram meant divine or pure and its name is the root of the word natron, which was used to refer to washing soda, or sodium carbonate decahydrate, as we would know it today. Sodium carbonate was used in soap, and also, in the process of mummification thanks to its water absorbing and bacteria killing pH control properties.

In medieval Europe, however, sodium carbonate was also used as a cure for headaches, and so took the name sodanum, from the Arabic suda, meaning headache. It was this terminology that inspired Sir Humphrey Davy to call the element sodium when he first isolated it by passing an electric current through caustic soda, or sodium hydroxide, in 1807. This process is known as electrolysis and using it Davy went on to isolate elemental potassium, calcium, magnesium and barium by a very similar method. Chemistry teachers often confuse children when they tell them about chemical symbols. Whilst ones like H, N, C and O all seem perfectly logical, abbreviating sodium to Na seems counterintuitive at first. However, if we consider the word natron, we can see where the abbreviated form came from. When isolated in metallic form, silvery white sodium is a violent element, immediately oxidising upon contact with air, and violently producing hydrogen gas which may burst into flame when brought into contact with water. It is one of the highly reactive group one elements that are named the alkali metals. Like the other alkali metals, it has a very distinctive flame test - a bright orange colour, from the D-line emission.

This is something you will have seen in all built up areas in the form of street lamps, which use sodium to produce the unnatural yellow light bathing our streets. This effect was first noted in 1860 by Kirchoff and Bunsen of Bunsen Burner fame. Almost all young chemists will have done a flame test at some point, and sodium chloride is a popular choice. Unfortunately, the intensity of the colour is such that if any of the compound is spilled into the Bunsen burner, it is cursed to burn with a blue and orange speckled flame seemingly forever. The reaction of sodium with water is a favourite demonstration, and clips of it abound on the internet. Sodium and its compounds have applications so diverse it would be impossible to mention them all here, a couple of examples include the fact that sodium is used to cool nuclear reactors, since it won't boil as water would at the high temperatures that are reached. Sodium hydroxide can be used to remove sulfur from petrol and diesel, although the toxic soup of by-products that is formed has led to the process being outlawed in most countries.

Sodium hydroxide is also used in biodiesel manufacture, and as a key component in products that remove blockages from drains. Baking soda actually contains sodium (it's in the name!) and its chemical name is sodium bicarbonate, where I'm sure you've come across it in baking or cooking where it undergoes thermal decomposition at above 70°C to release carbon dioxide - which then makes your dough rise. It is as an ion, however, that sodium really becomes important. An average human being has to take in around two grams of sodium a day - and virtually all of this will be taken in the form of salt in the diet. Sodium ions are used to build up electrical gradients in the firing of neurons in the brain. This involves sodium (and its big brother potassium) diffusing through cell membranes. Sodium diffuses in and is pumped back out, while potassium does the reverse journey. This can take up a huge amount of the body's energy - sometimes as much as 40 per cent. I'd like to end with a brief story which highlights the dual personality of sodium.

One man bought three and a half pounds of sodium metal from the internet and spent the evening reacting it with water in various shapes and sizes whilst he and his friends watched from a safe distance. The party was apparently a success, but he doesn't suggest hosting your own. The following day when the host came outside to check the area where he detonated the sodium was clear, he noticed that it was covered in swarms of yellow butterflies. After doing some research, he found that these butterflies had an interesting habit. The males search for sodium and gradually collect it, presenting it to their mates later as a ritual. So, that sums up the two faces of sodium. Its violent reactive nature contrasted with its use by amorous butterflies. Meera Senthilingam That was Southampton university's David Read with the two faced chemistry of sodium. Now next week, the chemical equivalent of train spotting. Brian Clegg It's easy to accuse the scientists who produce new, very heavy elements of being chemistry's train spotters. Just as train spotters spend hours watching for a particular locomotive so they can underline it in their book, it may seem that these chemists laboriously produce an atom or two of a superheavy element as an exercise in ticking the box.

But element 114 has provided more than one surprise, showing why such elements are well worth investigating. Meera Senthilingam And to find out why element 114 is worth the effort join Brian Clegg in next week's Chemistry in its element. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com . There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements . (End promo) Formulas and Nomenclature of Ionic and Covalent Compounds Ionic compounds are compounds composed of ions, charged particles that form when an atom (or group of atoms, in the case of polyatomic ions) gains or loses electrons. A cation is a positively charged ion An anion is a negatively charged ion. Covalent or molecular compounds form when elements share electrons in a covalent bond to form molecules. Molecular compounds are electrically neutral. Ionic compounds are (usually) formed when a metal reacts with a nonmetal (or a polyatomic ion). Covalent compounds are formed when two nonmetals react with each other.

Since hydrogen is a nonmetal, binary compounds containing hydrogen are also usually covalent compounds. Metal + Nonmetal —> ionic compound (usually) Metal + Polyatomic ion —> ionic compound (usually) Nonmetal + Nonmetal —> covalent compound (usually) Hydrogen + Nonmetal —> covalent compound (usually) Transition (B-group) and Post-Transition (Group IVA and VA) Metals These elements usually form ionic compounds; many of them can form more than one cation. (The charges of the common transition metals must be memorized; Group IV and V metal cations tend to be either the group number, or the group number minus two.) Many of these ions have common or trivial names formed from the stem of the element name (the Latin name in some cases) plus the ending -ic or -ous. (-ic endings go with the higher possible charge, -ous endings go with the lower possible charge). The systematic names (also known as the Stock system) for these ions are derived by naming the metal first, followed in parentheses by the charge written in Roman numerals. For the metals below that typically form only one charge, it is not usually necessary to specify the charge in the compound name.

For example, iron can form two possible ions, 2+ and 3+. The Fe2+ ion is known as the ferrous ion (common) or the iron(II) ion (systematic); the Fe3+ ion is known as the ferric ion (common) or the iron(III) ion (systematic). The mercury(I) cation is a special case; it consists of two Hg+ ions joined together, and so is always found as Hg22+. (Hence, mercury(I) chloride is Hg2Cl2, not HgCl, while mercury (II) chloride is HgCl2.) Ions of Some Transition Metals and Post-Transition Metals (Groups IVA and VA) Metal * But note that nitrogen does not follow this pattern (i.e., nitrate, NO3-) Some nonmetals form a series of polyatomic ions with oxygen (all having the same charge): ClO-, hypochlorite; ClO2-, chlorite; ClO3-, chlorate; ClO4-, perchlorate. The -ate forms (formula and charge) must be memorized.

In some cases, the -ate form has three oxygens, and in some cases four oxygens. The charge is the same for the entire series. The -ite form has one less oxygen that the -ate form. The hypo- stem -ite form has two less oxygens than the -ate form. The per- stem -ate form has one more oxygen than the -ate form. The -ide form is the monatomic anion (see Main-Group Nonmetals ) The general rules for such series are summarized in the table below: Formula Writing Formulas of Ionic Compounds The cation is written first, followed by the monatomic or polyatomic anion. The subscripts in the formula must produce an electrically neutral formula unit. (That is, the total amount of positive charge must equal the total amount of negative charge.) The subscripts should be the smallest set of whole numbers possible. If there is only one of a polyatomic ion in the formula, do not place parentheses around it; e.g., NaNO3, not Na(NO3).

If there is more than one of a polyatomic ion in the formula, put the ion in parentheses, and place the subscript after the parentheses; e.g., Ca(OH)2, Ba3(PO4)2, etc. Remember the Prime Directive in writing formulas: Ca(OH)2 ï¿½ CaOH2 ! Molecular Masses from Chemical Formulas The molecular mass, or molecular weight of a compound (measured in atomic mass units, amu) is obtained by adding up the atomic masses of all of the atoms present within a unit of the substance. For ionic compounds, the term formula mass or formula weight is used instead, since there aren't really any molecules present. The molecular/formula mass is numerically equal to the mass of one mole of the substance. For example, the molecular weight of water would be obtained by the following process: Molecular mass of H2O = (2 x atomic mass of H) + (1 x atomic mass of O) = (2 x 1.00797) + (1 x 15.9994) amu = 18.02 amu What Is the Difference Between Sodium and Salt?

What Is the Difference Between Sodium and Salt? What Is the Difference Between Sodium and Salt? Difference Between Salt and Sodium in Sodium Chloride These are cubic crystals of table salt or sodium chloride. Salt contains sodium, but it also contains chlorine, so only part of the mass of salt is sodium. Björn Appel By Anne Marie Helmenstine, Ph.D. Technically salt can be any ionic compound formed by reacting an acid and a base, but most of the time the word is used to refer to table salt, which is sodium chloride or NaCl. So, you know salt contains sodium, but the two chemicals aren't the same thing. What Is Sodium? Sodium is a chemical element . It is very reactive, so it isn't found free in nature. In fact, it undergoes spontaneous combustion in water, so while sodium is essential for human nutrition, you wouldn't want to eat pure sodium! When you ingest salt, the sodium and the chlorine ions in sodium chloride separate from each other, making the sodium available for your body to use. Sodium in the Body Sodium is used to transmit nerve impulses and is found in every cell of your body.

The balance between sodium and other ions regulates the pressure of cells and is related to your blood pressure, too. How Much Sodium Is in Salt? Because sodium levels are so critical to so many chemical reactions in your body, the amount of sodium you eat or drink has important implications for your health. continue reading below our video Test Your General Science Knowledge If you are trying to regulate or limit your intake of sodium, you need to realize the quantity of salt you eat is related to the amount of sodium, but is not the same. This is because salt contains both sodium and chlorine, so when salt dissociates into its ions, the mass is divided (not equally) between sodium and chlorine ions. The reason salt isn't just half sodium and half chlorine is because a sodium ion and a chlorine ion don't weight the same amount. Sample Salt and Sodium Calculation For example, here is how to calculate the amount of sodium in 3 grams (g) or salt.

You will notice 3 grams of salt does not contain 3 grams of sodium, nor is half the mass of salt from sodium, so 3 grams of salt does not contain 1.5 grams of sodium: Na: 22.99 grams/mole Molecules, Mixtures, & Compounds - Chemistry Teaching Tip Like 39 Dislike 34 The universe is made up of atoms, the tiny building blocks of matter. This computer screen is made up of atoms and so are your eyes and the rest of your body! In the last 110 years, scientists have discovered that atoms themselves are made up of even smaller particles: an atom has a central nucleus made up of protons and neutrons, and surrounded by electrons. These parts are so incredibly small that scientists can only believe that they are there, based on the behaviors that atoms display. Electron microscopes allow scientists to "see" highly magnified images of some atoms, but not the smaller particles that form the atom. Elements are the simplest substances in nature that cannot be broken down into smaller parts by normal chemical means. They contain only atoms of the same type, ones that have identical chemical properties.

There are at least 90 naturally-occurring elements, plus man-made ones. If you look at a periodic table , you'll see the names of each of these elements and some of their properties (such as mass, or how heavy the atom is). Molecules & Compounds When atoms from different elements are joined together in groups, they form molecules. The atoms in molecules bind together chemically, which means that the atoms cannot be separated again by physical means, such as filtration. The molecule has different properties from the elements from which is was made. A water molecule is not three separate atoms, two hydrogen (H) and one oxygen (O), but it is actually a unique H2O molecule with its own set of distinct properties. Like elements that are formed of atoms of the same sort, compounds are formed of molecules of the same sort. The elements can be combined into about 2 million different compounds! Did you know that eggshells are made up of a calcium carbonate compound? And citric acid, which is found in oranges and other citrus fruit, is a compound of carbon, hydrogen, and oxygen atoms. Your kids might find it helpful to do a science research project finding other common compounds around your house.

Make hypotheses and do research using a chemistry reference book, web site, or text book to find out the answers. There are more carbon compounds than compounds of any other element. Organic compound is the name for the carbon compounds found in all living things. Mixtures - A Bit of This and That All matter can be classified into two categories: pure substances and mixtures. A pure substance consists of a single element or compound. Iron is formed only of iron (Fe) atoms; table salt is formed only of sodium chloride (NaCl) molecules. A mixture, however, is made up of different compounds and/or elements. When salt is added to water to make saltwater, it becomes a mixture. The salt and water molecules do not combine to form new molecules, but only "mix" together while still retaining their identities. Air is also a mixture, containing just the right amounts of nitrogen, oxygen, and other gases for life on Earth. Not all mixtures have the same composition throughout. Salt water does, but Italian salad dressing does not--the parts separate and are not perfectly blended or homogenous. Mixtures of metals are called alloys (bronze is an alloy of copper and tin); liquid mixtures (such as saltwater) are called solutions.

The substances that make up a mixture can be separated by physical means because they have different physical properties (such as different melting points) and are not chemically bonded. A mixture can be separated into its parts in a variety of ways, including decantation (letting the sand in a mixture of water and sand settle, and then draining off the water, for example), filtering, and evaporation. You can use a kitchen funnel and coffee filter for filtration, and either use sunlight or low heat for evaporation. Try out these methods on saltwater and a sand and water mixture to see how they work and compare the results. Evaporation will work for both saltwater and sand and water solutions, but filtration will not work for saltwater. Can you think of other examples where a separating method will work for one mixture and not another? Another one to try is lemon juice, a mixture of water and citric acid; what do you think happens when it is boiled? The water evaporates and eventually leaves nothing but citric acid crystals. A Chemical By Any Other Name... The chemical formula for a molecule tells how many atoms and what types of atoms the molecule is made up of. How many atoms are in a molecule of AlSO4 (aluminum sulfate)?

There is one aluminum (Al), one sulfur (S), and four oxygen (O) for a total of six atoms. What is the formula for ammonium chloride? Since it contains one nitrogen (N), four hydrogen (H), and one chlorine (Cl), the chemical formula is NH4Cl. To familiarize your kids with the periodic table and the abbreviations for elements, make a game of answering questions like this. Figure out the number of atoms for CaOH2, FeCl2, K3FeCN6, and the chemical formulas for a compound with two sodium, one calcium, and three oxygen atoms and a compound with one iron and three chlorine atoms. Have you ever wondered what to call a chemical compound, such as CaOH2? There are a few general rules that can help you. Start with the name of the first atom, Ca. That's the element calcium. Then, take the next atom and replace the ending with "ide." Oxygen (O) becomes "oxide". As with many rules, though, there are exceptions! In this case, the first part of the name for the last atom, hydrogen (H), is tacked on so that the correct chemical name is calcium hydroxide.

Here's one your kids should be able to figure out with just a periodic table: what is the chemical name for NaCl? Prefixes, the part added to the beginning of a word, can help you figure out names and formulas, too. Mono means one, di means two. So a compound with two of the same molecule (represented by a subscript 2) would have "di" before that molecule name. What would you call CO2? How many oxygen atoms are in carbon monoxide? What is the chemical formula for dicarbon dihydride? A mole is a measure of chemical substances. There are 602,300 million trillion (6.023 x 1023) atoms or molecules in one mole. A mole of any two elements will have a different mass, but the same number of particles. If you look up gold (Au) on a periodic table, you'll see it has an atomic mass of 107.9. To measure out one mole, you should weigh out 107.9 grams of gold. The atomic mass of sodium (Na), on the other hand, is 23.0 and so one mole is 23 grams of sodium.

Both gold and sodium have the same number of particles in one mole, though: 6.023 x 1023. Atoms, elements and compounds KENT GEOLOGISTS' GROUP Atoms, Elements and Compounds Kent Geology Atoms and Elements An atom consists of two main parts. Firstly a nucleus in which protons, having a positive charge, and neutrons having no charge, are tightly bound together. Secondly, surrounding the nucleus, are one or more electrons in shells, each of which has an associated energy level. The number of electrons is always equal to the number of protons, so the atom has no resultant charge. Atoms are very very small, typically about one ten millionth of a millimetre in diameter! The nucleus is even smaller; the diameter of the atom being about 10,000 times that of the nucleus. Because atoms are so small their dimensions are measured in nanometres. A nanometre is one millionth of a millimetre. The masses of the proton and neutron are approximately equal and are about 1800 times the mass of an electron. The simplest element, Hydrogen, has one proton and one electron.

The next element, Helium, has two protons, two neutrons and two electrons. Electrons are located in orbits or shells, each of which has a maximum complement of electrons. The numbers are two in the first, eight in the second, eight in the third and so on. When the outer shell has a full complement of electrons the element is chemically inactive. These elements are the Noble (or inert) Gases. From stability considerations the outer electron shell of other elements is 'incomplete'. These elements tend to react with other elements to achieve a complete outer shell by giving up, acquiring or sharing outer shell electrons. Chemical reactions between elements always involve the outer shell electrons. These are called the 'valency electrons'. The total number of electrons is called the 'atomic number' of the element. Compounds Compounds are products formed by chemical reaction between elements. A compound is not a mixture but a new substance, having different properties from its constituent elements. For example, sodium chloride, common salt, is a compound of sodium (a soft silvery metal) and chlorine (a greenish gas). It doesn't look or behave like either of its constituents. Explained very simply, sodium has atomic number 11.

It therefore has 11 electrons of which 2 are in the innermost shell, 8 in the second shell and 1 in the third. A complete outer shell would have 8 electrons. Sodium has one electron surplus to that required for stability and will react with other atoms. The sodium atom is shown in the diagram on the left with a blue nucleus. Chlorine (shown in the diagram with a green nucleus} has atomic number 17; that is, it has 17 electrons. Two electrons are in the first shell, 8 are in the second shell, leaving 7 electrons in the third shell. This is one short of the 8 electrons needed for a complete shell and therefore for stability. When sodium and chlorine combine chemically to form sodium chloride, the 'spare' electron in the outer shell of the sodium atom is given up to the outer shell of the chlorine atom. This gives both atoms a complete outer shell with 8 electrons, thus forming a stable compound. In losing an electron the sodium atom becomes positively charged and forms a sodium ion, written Na1+.The chlorine atom, acquiring an electron, becomes negatively charged and forms a chlorine ion, written Cl1-.

In solution, ions combine, negative charge attracting positive charge to form compounds. The way in which atoms and ions combine is determined by chemical bonding (see link below). The difference between the number of electrons in the outer shell of an atom and that required for a complete outer shell is a measure of an atom's ability to combine with others and is called its 'valency'. Sodium and chlorine (having one spare electron and one electron short respectively) have a valency of one. In simple terms, atoms can be thought of as spheres of different sizes. In forming compounds, these spheres pack together in the most compact configuration possible. In sodium chloride, the sodium and chlorine atoms form a cubic, crystal lattice as shown in the figure on the right. The compounds that can be formed will depend on the relative sizes of the atoms. If the atoms trying to form a compound are too far apart the bonding may be too weak; when close enough to form an adequate bond they may interfere. Thus not all atoms are compatible to form compounds even if their valencies suggest that it would be possible. Rockï¿½-ï¿½Forming Silicates Silicates are the most abundant rock-forming minerals.

The silicate ion is one in which one silicon atom (valency=+4) is attached to four oxygen atoms (valency=-2). The ion, SiO4 is tetrahedral in shape, that is it has four faces. with the four oxygen atoms occupying the four corners of the tetrahedron and the silicon atom at its centre. Each of the oxygen atoms has a spare valency bond.The way in which the four oxygen atoms of each tetrahedron are shared, as the silicate tetrahedra combine, determines the form of the resultant silicate mineral. In Nesosilicates (Greek, nesos = an island) such as Olivine, no oxygen links are shared and the SiO4 form is retained. In Sorosilicates (Greek, soros = a group) such as Melilite or Hemimorphite, two tetrahedra share one oxygen atom to form an Si2O7 ion. In the Cyclosilicates (Greek, cyclo = a ring) such as Tourmaline, the tetrahedra are joined in rings, each sharing two oxygen atoms.

In the Phyllosilicates (Greek, phyllo = a leaf) such as Talc and Mica, the tetrahedra are joined in sheets, sharing three oxygen atoms. Finally if all four oxygen atoms of each tetrahedron are shared, the tetrahedra form a three-dimensional structure as in the tectosilicates (Greek, tecto = a framework). Quartz and the Feldspars are tectosilicates. What is Sodium Chloride? - Definition, Structure & Formula - Video & Lesson Transcript | Study.com What is Sodium Chloride? - Definition, Structure & Formula Watch short & fun videos Start Your Free Trial Today An error occurred trying to load this video. Try refreshing the page, or contact customer support. You must create an account to continue watching Register for a free trial Are you a student or a teacher? I am a student Start Your Free Trial To Continue Watching As a member, you'll also get unlimited access to over lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Coming up next: Mole-to-Mole Ratios and Calculations of a Chemical Equation You're on a roll.

Keep up the good work! Your next lesson will play in 10 seconds 0:12 What is a Salt? 0:45 Characteristics of… Add to Add to Add to Want to watch this again later? Log in or sign up to add this lesson to a Custom Course. Custom Courses are courses that you create from Study.com lessons. Use them just like other courses to track progress, access quizzes and exams, and share content. Teachers Organize and share selected lessons with your class. Make planning easier by creating your own custom course. Students Create a new course from any lesson page or your dashboard. From any lesson page: Click "Add to" located below the video player and follow the prompts to name your course and save your lesson. From your dashboard: Click on the "Custom Courses" tab, then click "Create course". Next, go to any lesson page and begin adding lessons. Edit your Custom Course directly from your dashboard. Personalize: Name your Custom Course and add an optional description or learning objective. Organize: Create chapters to group lesson within your course. Remove and reorder chapters and lessons at any time. Share your Custom Course or assign lessons and chapters.

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One of the most important salts in nature and biological systems is sodium chloride. Let's look at sodium chloride and discuss what makes it such a valuable salt in nature. Characteristics of a Sodium Chloride Sodium chloride is formed when sodium atoms interact with chlorine atoms. When this occurs, sodium will donate an electron (which is a negatively-charged particle) to chlorine. This makes sodium slightly positive and chlorine slightly negative. Opposite charges attract, right? So then, sodium ions will attract chloride ions and form an ionic bond. By the way, chloride is the term used to designate the anion form of chlorine. The result is a crystallized salt that has properties that are different from the two parent elements (sodium and chlorine). The chemical formula for sodium chloride is NaCl, which means that for every sodium atom present, there is exactly one chloride atom. Sodium chloride has a molar mass of 58.44 grams per mole. It appears as a solid, clear crystal with little or no odor. As a salt, sodium chloride dissolves well in water and the ions in the crystals will separate when in solution. Have you ever added salt to a pot of boiling water, maybe to make pasta?

You can see how instantly the little crystals dissolve, or break apart in the water. Sodium chloride molecules can also stack on top of each other in a structure known as a lattice and the solid crystals of sodium chloride will contain this lattice-type arrangement. Sodium chloride has many commercial and biological uses. Let's discuss a few of these. Commercial Uses of Sodium Chloride Sodium chloride can be used in many commercial products as well as in public works projects. For example, whenever the temperature drops close to freezing, sodium chloride is often used to prevent ice buildup on the roads and bridges in order to preserve safe driving conditions. Sodium chloride is also used in the production of several commercially-important metals, such as copper, steel, and aluminum. Other uses of sodium chloride include glass production, rubber production, and hardening of soil during construction. × Sodium Chloride The Molecular Biology of Nutrition The Sodium/Chlorine Reaction What happens when you combine chlorine (a poisonous gas) with sodium (a toxic metal)? You get table salt (sodium chloride), a crystal that dissolves into two essential nutrients. How are two toxic substances transformed into nutrients? They combine as atoms, and separate as ions.

When sodium and chlorine atoms come together to form sodium chloride (NaCl), they transfer an electron. The sodium (Na) atom transfers one electron to the chlorine (Cl) atom, so that they both have full outer shells. With filled outer shells they are no longer chemically active and can't form covalent bonds to become part of a molecule. With the transfer of the electron, however, they become electrically charged, and combine into salts through the formation of ionic bonds. The sodium ion now has only ten electrons, but still has eleven protons. This upsets the balance of charges between the protons and electrons, which causes the sodium atom to have a net positive charge. When this happens, the atom is called a positive ion. The chloride ion now has eighteen electrons and seventeen protons, so it's become a negative ion. Because the sodium ion has a positive charge, and the chlorine ion has a negative charge, they are attracted to each other, and form an ionic bond. Ions form salts, not molecules, but they perform many important functions in nutrition. Sodium and Chlorine Sodium and chlorine are both very reactive in their pre-ionic states.

They will transfer electrons and (in dry conditions) form salts when they encounter each other. Each one will react with other elements if they don't find each other first, so they are seldom found in nature in their reactive states. They usually arrive on our plates together as table salt (or it's dissolved ions). In our bodies, however, they aren't bound together as salt, but dissolve back into individual ions in water. And while they complement each other in many biological processes, they also have their separate roles to play. We've already seen what happens when sodium and chloride combine. Now we'll look at each of them individually. First we'll examine them as reactive atoms, and see why they are toxic in this state. Then we'll look at them in their ionic form and find out why they have nutritional value. The Sodium Atom When most people think of sodium, they think of table salt. While table salt contains an ionized form of sodium (in combination with chloride), non-ionized "metallic" sodium has a very different set of chemical properties than the sodium ions in table salt.

We examine the chemical properties of sodium in its reactive (toxic) state here, and look at sodium in its ionic (nutritional) state in the next section. The sodium atom (Na) has eleven protons and eleven electrons, giving it a neutral (balanced) electrical charge. It has only one electron in its outer shell, however, which makes it chemically reactive. To be chemically stable it needs to have a full outer shell. It's easier to get rid of one outer electron than it is to aquire seven more electrons, so it looks to give up the electron. The outer electrons of each sodium atom aren't desired by any of the sodium atoms, so a cloud of unwanted electrons form. The random motion of the electrons in this cloud cause shifts in the electrical properties of the individual atoms, which in turn cause the atoms to be mildly attracted to each other. These small electrical imbalances initiate metallic bonding at room temperature, causing the atoms to clump together into a soft metal you can cut with a knife. The combination of metallic sodium atoms with each other is relatively uneventful. To understand why metallic sodium is so reactive, let's see what happens when it comes into contact with water.

Water (H2O) is a molecule consisting of two hydrogen atoms covalently bonded to an oxygen atom. These bonds are formed because the oxygen atom needs two electrons to fill its outer shell, and each hydrogen atom needs one electron. The formation of the water molecule conveniently fills the outer shells of all three atoms, which is why water molecules form from the two gases. Metallic sodium in Water The molecular bonds formed by the hydrogen and oxygen atoms in water are so weak they often break apart due to random thermal energy. So when sodium wants to get rid of its extra electron, water is an easy target. One of the hydrogen/oxygen bonds in water is easily broken, and the sodium atom donates its unwanted electron, filling the vacated space in oxygen's outer shell. Because the donated electron moved from a high energy state around sodium to a lower energy state around oxygen, extra energy is released. This ScienceFix video shows how explosive the chemical reaction can be. The Sodium Ion Table salt contains sodium in its ionic form. That's why it doesn't explode on contact with water, and why it has nutritional value. It complements the chloride ion because they have opposite charges which balance each other in many biological processes.

Sodium also complements potassium, because while they are both positive ions, they are also chemically different. The chemical differences between sodium and potassium are useful in controlling diffusion across our cell membranes, while the electrostatic differences between sodium and chloride are important in maintaining an electrical imbalance across those same cell membranes. To see how sodium uses these differences to enable signal transmission in nerve and muscle cells, see the article on diffusion . Sodium is an essential nutrient in animal cells, but it's possible to get too much of a good thing. While low sodium levels can cause muscle cramps due to nerve and muscle cells not being able to control signal transmission and reception, too much sodium can cause problems like high blood pressure. When we consume sodium, it's absorbed into the bloodstream and extracellular spaces. While it's normal for the extracellular spaces to have a much higher concentration of sodium than is found inside the cell, (the imbalance is used for signal transmission), it can be taken too far. If too much sodium builds up in the bloodstream and extracellular fluids, it will dilute water concentrations outside of the cells. Water will diffuse from high concentrations inside the cell to the lower concentrations outside of the cell, including the bloodstream. This causes cell dehydration and higher blood pressure.

When water flows out of nerve cells that are located in the hypothalamus, osmoreceptors in those cells trigger the thirst sensation. By drinking water, we dilute the sodium in the bloodstream, which reverses the flow of water back into the cells. The kidneys monitor sodium levels in the bloodstream and eventually remove the excess sodium and water, placing them in the urine. Despite this corrective process, routine overconsumption of sodium can result in chronic high blood pressure, since the kidneys can only compensate so much. The Chlorine Atom The center of the chlorine (Cl) atom contains seventeen protons which are surrounded by seventeen electrons, giving it a neutral (balanced) electrical charge. It has seven electrons in its outer shell, and needs one more, which makes it chemically active. It will fill its outer shell by pairing up with other chlorine atoms to form small molecules, but these covalent bonds are weak and chlorine will abandon them when it comes into contact with an element from which it can steal an electron. Due to its chemical properties it's a gas at room temperature, making it especially dangerous. It's so toxic when inhaled, it was used as a chemical weapon in the first World War.

We use it today in small amounts as a disinfectant. When a chlorine atom comes into contact with a hydrogen atom it forms a molecule of hydrogen chloride (HCl). This enables chlorine to fill its outer electron shell with hydrogen's electron, but hydrogen's nucleus (a proton) also comes along for the ride. When hydrogen chloride comes into contact with water (H2O) it transfers the proton to the water molecule, which creates two charged molecules (HCl becomes Cl-, and H2O becomes H3O+). These two molecules dissolve into additional water molecules to form a highly acidic solution called hydrochloric acid. If chlorine gas is inhaled into the lungs, it will combine with hydrogen (from water molecules) to create hydrogen chloride, and then react with water to form hydrochloric acid, causing severe damage. If hydrogen chloride is excreted into the stomach, it combines with water to form hydrochloric acid, an aid to digestion. What's the difference between a toxin and a nutrient? Sometimes it's nothing more than location! The Chloride Ion Once you get chlorine into its ionic form (chloride) it offers many nutritional benefits.

As a negative ion, chloride not only plays an important role in signal transmission, but also chemically reacts with hydrogen and water to create hydrochloric acid, a solution that helps with digestion. Hydrochloric acid is created when Parietal cells that line the stomach use the chloride ion (Cl-) as an aid to digestion by combining it with a hydrogen ion (a proton, H+) to become hydrogen chloride (HCl). When the parietal cells secrete the hydrogen chloride into the stomach, it chemically reacts with water. In this reaction the hydrogen chloride breaks back down into the chloride ion by transfering its proton to the water molecule. The water molecule (H2O) becomes a hydronium ion (H3O+) when it gains the proton. In the presence of additional water in the stomach, these two oppositely charged ions (chloride and hydronium) stay dissolved. This combination of water, chloride and hydronium forms the solution called hydrochloric acid. Hydrochloric acid is the main ingredient of gastric (stomach) acid, which digests our food.

Gastric acid's low PH level (about 1 or 2) denatures (unfolds) the proteins in our food so that enzymes in the stomach can break apart (digest) the bonds that hold the amino acids together. Chloride (a negative ion) also interacts with sodium and potassium (both positive ions) to create and maintain the electrostatic imbalances which make signal transmissions and the transport of nutrients across the cell membrane possible. I examine these interactions (including chlorine's role), in the article on diffusion . Most of the chloride in our diet comes from table salt (sodium chloride), but it's present in a wide variety of foods. In whole foods it's especially high in tomatoes, lettuce and olives. Table Salt Table salt (sodium chloride) is a very important part of our diet. In addition to its nutritional qualities, it is used as a preservative and a flavor enhancer. Many of our foods would taste very different without it, even foods that we don't think of as being salty, like bread and milk. It's such an important part of our diet the tongue has evolved a specialized receptor to detect it. The words salt and table salt refer to two different things.

Salt refers to an entire class of chemical compounds that are held together by ionic bonds (in contrast to a molecule, which is held together by covalent bonds), while table salt refers to a specific compound (sodium chloride). Both sodium and chloride (in ionic form) combine with other substances into other kinds of salts like potassium chloride or sodium bicarbonate (baking soda). Salts can also be created from elements that don't include either sodium or chloride. The weak ionic bonds between sodium and chloride are dissolved by the stronger polarity of the water molecule, so sodium chloride doesn't exist as a salt inside the body. While sodium and chloride interact with each other in our bodies, they act as separate elements. Their nutritional value is derived not only from their ability to react with each other, but also with other atoms or molecules. These characteristics make processes like the regulation of fluid pressures and the transmission of electrical impulses possible. Why Plants Are Low in Sodium The presence of chloride, potassium and sodium in the right proportions creates an environment that enables the cell to perform it's biological functions. This is one of the reasons they are an essential part of animal diets. Sodium, however, isn't an essential nutrient for plants.

While plants can (and do) use sodium when it's available, they prefer potassium. Both sodium and potassium are positive ions, so potassium can fill in for sodium when it comes to functions like electrostatic charge. Yet they still have significant differences in their chemical properties. We need sodium to setup concentration gradients for the transmission of signals in nerve and muscle cells. Plants don't have these types of cells, so they don't need sodium for signal transmission. Animals use sodium/potassium pumps to decrease fluid pressure levels inside their fragile cell walls to keep them from bursting. Plants, on the other hand, have thicker cell walls that not only stand up to the extra pressure, but count on it to help maintain structural integrity (that's why leaves wilt when they don't get enough water). Plants use proton pumps instead of sodium/potassium pumps to maintain proton gradients, so they don't depend on sodium for any critical processes. Even more important is sodium's toxic effect on plants. Sodium is toxic for both animals and plants in high concentrations. While animals can compensate for high levels of sodium intake by removing it from their body through the kidney, plants don't have that option.

In addition, animals can stop consuming sodium, while plant roots automatically absorb it from the ground during water uptake. If sodium is in the soil in large amounts, the plant will have no way of not absorbing it, and no easy way of getting rid of it once it's absorbed. High enough levels of sodium will pull water out of cells, which is deadly for all living things. That's how it works as a preservative. Beef jerky doesn't spoil if kept dry because bacteria can't maintain enough moisture inside their cells to procreate in the presence of that much salt. That's also why people can't survive on sea water. Our kidney can remove excess salt, but only by flushing it out with water. The sodium content of sea water is so high, it requires more water to flush it out than is contained in the sea water. It makes up the difference by using water from your body, which dehydrates you. Plant roots use osmosis to bring water up into the plant. That's another reason why too much sodium in the soil is bad for plants. Sodium reverses the direction of osmosis, pulling water back out of the plant and into the soil.

For all of the above reasons, all fresh fruit and vegetables are low in sodium, and many are high in potassium. Canned vegetables have lots of sodium because it's added later when processed to make it taste better. The plant didn't put it there.

Question: Common Salt is a compound formed from two elements; one is Sodium, which is the other?
Answer: CHLORINE